I had a host that wasn’t backing up at all and found the following error message within the CrashPlan engine_error.log located in /usr/local/crashplan/log
Exception in thread "W87903837_ScanWrkr" java.lang.NoClassDefFoundError: Could not initialize class com.code42.jna.inotify.InotifyManager
From what I could tell it was related to a CentOS 6.x upgrade that may have set the noexec on /tmp which wasn’t set previously.
The error sees to be related to writing files to the /tmp directory, the following two websites I found by a simple Google search revealed this problem.
You have to update the CrashPlan Java options to store its temporary that isn’t mounted as “noexec” by your system
Open up /usr/local/crashplan/bin/run.conf and add the following to the end of SRV_JAVA_OPTS